The corn snake (Pantherophis guttatus) is a North American species of rat snake that subdues its small prey by constriction. It is found throughout the southeastern and central United States. Their docile nature, reluctance to bite, moderate adult size, attractive pattern, and comparatively simple care make them popular pet snakes. Though superficially resembling the venomous copperhead and often killed as a result of this mistaken identity, corn snakes are harmless and beneficial to humans. Corn snakes lack venom and help control populations of wild rodent pests that damage crops and spread disease.
The corn snake is named for the species’ regular presence near grain stores, where it preys on mice and rats that eat harvested corn. The Oxford English Dictionary cites this usage as far back as 1675. Some sources maintain that the corn snake is so-named because the distinctive, nearly-checkered pattern of the snake’s belly scales resembles the kernels of variegated corn. Regardless of the name’s origin, the corn reference can be a useful mnemonic for identifying corn snakes.
Adult corn snakes have a body length of 61–182 centimetres (2.00–5.97 ft). In the wild, they usually live around 6–8 years, but in captivity can live to an age of 23 years or more. They can be distinguished from Copperhead snakes by their brighter colors, slender build and lack of heat-sensing pits.
Until 2002, the corn snake was considered to have two subspecies: the nominate subspecies (Pantherophis guttatus guttatus) described here and the Great Plains rat snake (Pantherophis guttatus emoryi). The Great Plains rat snake has since been split off as its own species (Pantherophis emoryi), but is still occasionally treated as a subspecies of the corn snake by hobbyists.
It has been suggested that Pantherophis guttatus can be split into three species: Pantherophis guttatus, Pantherophis emoryi (corresponding with the subspecies Pantherophis guttatus emoryi) and Pantherophis slowinskii (occurring in western Louisiana and adjacent Texas).
Pantherophis guttatus was previously placed in the genus Elaphe, but Elaphe was found to be paraphyletic by Utiger et al., leading to placement of this species in the genus Pantherophis. The placement of Pantherophis guttatus and several related species in Pantherophis rather than Elaphe has been confirmed by further phylogenetic studies. Many reference materials still use the synonym Elaphe guttata. Molecular data has shown that corn snakes are actually more closely related to king snakes (genus Lampropeltis) than they are to the Old World rat snakes with which they were formerly classified. Corn snakes have even been bred in captivity with California king snakes to produce fertile hybrids known as “Jungle corn snakes”.
Wild corn snakes prefer habitats such as overgrown fields, forest openings, trees, palmetto flatwoods and abandoned or seldom-used buildings and farms, from sea level to as high as 6,000 feet. Typically, these snakes remain on the ground until the age of 4 months old but can ascend trees, cliffs and other elevated surfaces. They can be found in the southeastern United States ranging from New Jersey to the Florida Keys and as far west as Texas.
In colder regions, snakes hibernate during winter. However, in the more temperate climate along the coast they shelter in rock crevices and logs during cold weather, and come out on warm days to soak up the heat of the sun. During cold weather, snakes are less active and therefore hunt less.
Corn snakes are relatively easy to breed. Although not necessary, they are usually put through a cooling (also known as brumation) period that takes 60–90 days. This is to get them ready for breeding and to tell them that its time to reproduce. Corns brumate at around 10 to 16 °C (50 to 61 °F) in a place where they can not get disturbed and little sunlight.
Corn snakes usually breed shortly after the winter cooling. The male courts the female primarily with tactile and chemical cues, then everts one of his hemipenes, inserts it into the female, and ejaculates his sperm. If the female is ovulating, the eggs will be fertilized, and she will begin sequestering nutrients into the eggs, then secreting a shell.
Egg-laying occurs slightly more than a month after mating, with 12–24 eggs deposited into a warm, moist, hidden location. Once laid the adult snake abandons the eggs and does not return to them. The eggs are oblong with a leathery, flexible shell. Approximately 10 weeks after laying, the young snakes use a specialized scale called an egg tooth to slice slits in the egg shell, from which they emerge at about 5 inches in length.
Like all snakes, corn snakes are carnivorous, and in the wild they will eat every few days. While most corn snakes will seek and consume small rodents, such as the White-footed Mouse, they may also be found eating reptiles or amphibians, or climbing trees in order to find unguarded bird eggs.
Corn snakes are one of the most popular types of snakes to keep in captivity or as pets. Their size, calm temperament, and ease of care contribute to this popularity. Captive corn snakes tolerate being handled by their owners, even for extended periods of time. A corn snake’s space requirements are low since a medium-sized vivarium provides enough room for a full grown corn snake. Corn snakes enjoy hiding and burrowing which is usually accommodated with a loose substrate (such as Aspen wood shavings or newspaper) and one or more hide boxes. Captive corn snakes are generally fed pre-killed or stunned feeder mice. This is because captive-bred rodents reduce the risk of exposing the snake to pathogens or live prey-induced injuries.